Earth Overshoot Day is the date by which humanity has used more of the Earth’s resources in a given year than our planet will be able to replenish that year. We are overfishing, overharvesting forests, and emitting more carbon dioxide into the atmosphere than forests can sequester.

In the year I was born, Earth Overshoot Day occurred in mid October.

Fast forward to the year I started secondary school, and it had already crept forward by several weeks, into late September.

Just five years later – the year I did my GCSEs and became interested in environmental issues, with the help of geography teachers and some excellent futurist fiction – Overshoot Day had jumped forward by another full month into late August.

By the time I finished undergrad in 2012, another 20 days had been lost. Then by last year it had crept forward another week. That means that for the rest of the year we were eating into the planet’s reserves and decreasing its ability to support us.

Obviously I don’t want to claim that the advance of this date was due to me growing up! But it is sobering to think about the dramatic changes that have occurred alongside my own milestones. How do the dates match up to your own lifetime experiences? What changes have you seen in the world around you since then?

Our demand on the Earth is sometimes called our ecological footprint, and our ‘supply’ is the Earth’s biocapacity. This includes resources like timber and fish, but also the planet’s ability to absorb our waste. Waste includes things like plastics, but also pollution such as the extra carbon dioxide and other climate-changing greenhouse gases we emit into our atmosphere – which in turn reduces the planet’s productive ability the following year. For example, our warming planet is making weather more extreme and less seasonal, meaning that crops and wildlife are less able to survive. The extra CO2 is also making oceans more acidic, which impacts the survival and reproductive ability of crucial species in ocean food chains (or more accurately, food webs).

Is there any good news?

Well, we might take some hope from the fact that in the past few years, the advance of ‘overshoot’ has slowed. There are several explanations for this. If you look at the date change over time, you can clearly see Overshoot Day being pushed backwards (improving) in years that correspond to financial crises in the early 70s, early 80s and 2007-2009 – times when industry had to slow or pause its consumption and pollution.

It can also relate to better efficiency. Yet, despite industry efforts to be more efficient with resources, the absolute amount of resources we are using has not shrunk. This is the ‘Jevons Paradox’ – a term from economics which explains how, when producers make more from less, that resource becomes more valuable, because it produces more goods from the same amount of resource. Then we start to use more of it overall, because of the enticing profits. Efficiency on its own will not be enough to move the date of overshoot backwards.

Also, it’s important to note that this is not just about population increase. Affluent countries, whose populations are not growing, and in some cases are even shrinking, are the ones driving the increased consumption. They’re using several planets’ worth of resources while many developing countries use far less than their fair share per person. Overshoot is about how we distribute resources, and how we manage the world’s productive systems.

What can we do about it?

First, focus on the reduce part of the ‘reduce, reuse, recycle’ hierarchy! It’s certainly possible to have just as good a quality of life without consuming so much. In fact, there’s an idea that having less ‘stuff’ can actually improve your wellbeing. Instead of buying physical stuff like that jacket you probably won’t wear, try rewarding yourself with local experiences – a walk in the woods, a massage, a concert. Buy services not products – get your favourite shoes fixed instead of buying painful new ones. Buy your friend a restaurant voucher for their birthday instead of a piece of novelty tat. Get yourself a bike instead of a car. Reduce your bills with clever water and energy-saving devices. If you want to systematise this approach for maximum impact, try our One Planet Living framework which makes it easy and enjoyable to adopt this kind of lifestyle.

Secondly, educate the next generation. There are guidelines for classroom activities that teachers can use to get pupils and students engaged with what ‘biocapacity’ and ‘overshoot’ really mean. If you do this in the next few days, you can get them to enter an international competition (below).

Finally, enter your guess for the date of Earth Overshoot Day 2019 by 22 May 2019. This is a competition where you can use Global Footprint Network’s open data platform and other information available on its website to help you come up with your best guess.

You don’t have to be a pupil or teacher to win this competition, but the winners last year were a team of three 18 year olds whose geography teacher had taken them through the classroom activity described above. The correct date will be announced on 5 June, which also happens to be World Environment Day 2019.

Our One Planet Living framework enables people to live happy, healthy lives within the natural limits of the planet, leaving space for wildlife and wilderness.

Check out the #movethedate campaign, also initiated by Earth Overshoot Day. Here people can make pledges for how they will help #movethedate and create a sustainable future.